MailWindow: Include all payment variants

Elwig/Windows/MailWindow.xaml.cs

@@ -129,7 +129,7 @@ namespace Elwig.Windows {
             };
             if (season != null) {
                 l.Add($"{DeliveryConfirmation.Name} {Year}");
-                l.AddRange(season.PaymentVariants.Where(v => !v.TestVariant).OrderBy(v => v.AvNr).Select(v => $"{CreditNote.Name} – {v.Name}"));
+                l.AddRange(season.PaymentVariants.OrderBy(v => v.AvNr).Select(v => $"{CreditNote.Name} – {v.Name}"));
             }
             AvaiableDocumentsList.ItemsSource = l;